Thermally processable imaging elements typically comprise a support bearing an imaging layer and various other layers such as backing, subbing and overcoat layers. The imaging element in a thermally processable imaging element typically is comprised of a mixture of a polymeric binder (such as poly(vinylbutyral)) with a variety of imaging components such as silver behenate, reducing agents and developers.
It is known to add various additives to the layers of thermally processable imaging elements. Such additives include plasticizers as disclosed, for example, in U.S. Pat. Nos. 3,893,860 5,468,603 and U.S. Pat. No. 5,527,758.
The use of plasticizers in polyvinyl butyral is known. For example Encyclopedia of Polymer Science and Engineering, H. Mark et al, eds, Vol 17, p. 156, J. Wiley and Sons, New York, 1989, teaches that a "wide variety of plasticizers is suitable for polyvinyl(butyral)," suggesting specific materials such as phthalates, phosphates, fatty acid esters, and polyester based materials as useful plasticizers.
It is also known to add plasticizers to other imaging elements. For example, U.S. Pat. No. 4,705,736 describes the use of plasticizers in a thermally developable diazotype film. The incorporation of the plasticizer increases development speeds during thermal processing.